Clock



FIG. 1 is a front elevational view of the clock showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The broken-line numerals of FIG. 1 are environmental only and form no part of the claimed design. 

The ornamental design for a clock, as shown and described. 